Support uninstalling JSON & PHP translation files #129

Feature Request

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing

The WordPress core performance team is working on the Performant Translations feature project, which aims to speed up translations by using PHP files instead of MO files. The goal is to get it ready for WordPress 6.5. If and when that support is added to WordPress core, *.l10n.php translation files need to be properly deleted on uninstall as well.

In addition to that, JSON translation files are not currently handled either, causing a lot of lingering files.

Describe the solution you'd like

• Delete .l10n.php translation files on uninstall
• Delete .json translation files on uninstall (maybe do a regex check or something to not delete the wrong files)